Sensor device removably attachable to a drug delivery device

ABSTRACT

A sensor device ( 2 ) is removably attachable to a drug delivery device ( 12 ). The sensor device comprises an array ( 20 ) of optical sensors arranged within the sensor device such that, when the sensor device is attached to the drug delivery device, the drug delivery device having a first movable element ( 14 ) which is configured to move along a path parallel to the longitudinal axis of the drug delivery device, each optical sensor is operable to detect light received at different locations along the linear path and to output a signal indicative of an amount of detected light; and circuitry ( 21 ) configured to receive the signals output from the optical sensors and, based on the received signals, to determine information associated with a location along the path of the first movable element.

FIELD

The invention relates to a sensor device removably attachable to a drugdelivery device such as an injection pen.

BACKGROUND

A variety of diseases exists that require regular treatment by injectionof a medicament. Such injection can be performed by using injectiondevices, which are applied either by medical personnel or by patientsthemselves. As an example, type-1 and type-2 diabetes can be treated bypatients themselves by injection of insulin doses, for example once orseveral times per day. For instance, a pre-filled disposable insulin pencan be used as an injection device.

Alternatively, a re-usable pen may be used. A re-usable pen allowsreplacement of an empty medicament cartridge by a new one. Either penmay come with a set of one-way needles that are replaced before eachuse. The insulin dose to be injected can then for instance be manuallyselected at the insulin pen by turning (dialing) a dosage knob andobserving the actual dose from a dose window or display of the insulinpen. The dose is then injected by inserting the needle into a suitedskin portion and pressing an injection button of the insulin pen. To beable to monitor insulin injection, for instance to prevent falsehandling of the insulin pen or to keep track of the doses alreadyapplied, it is desirable to measure information related to a conditionand/or use of the injection device, such as for instance information onthe injected insulin type and dose.

It has been described, for instance in WO 2011/117212, to provide asupplementary device comprising a mating unit for releasably attachingthe device to an injection/drug delivery device. The device includes acamera and is configured to perform optical character recognition (OCR)on captured images visible through a dosage window of the injection pen,thereby to determine a dose of medicament that has been dialed into theinjection device. In order for such a supplementary device tosuccessfully determine the dose, the dosage window must remainstationary. However not all drug delivery devices operate in this way.

SUMMARY

According to a first aspect of the invention there is provided a sensordevice removably attachable to a drug delivery device, the sensor devicecomprising:

an array of optical sensors arranged within the sensor device such that,when the sensor device is attached to the drug delivery device, the drugdelivery device having a first movable element which is configured tomove along a path parallel to the longitudinal axis of the drug deliverydevice, each optical sensor is operable to detect light received atdifferent locations along the linear path and to output a signalindicative of an amount of detected light; and

circuitry configured to receive the signals output from the opticalsensors and, based on the received signals, to determine informationassociated with a location along the path of the first movable element.

This can allow detection of the approximate longitudinal position of themovable element of the drug delivery device with a relatively simplearrangement in the sensor device. The rotational position of themoveable element or a related element can be detected through a separatesensor arrangement.

Each of the optical sensors may have a corresponding light sourcearranged to emit light towards the externally visible path when thesensor device is attached to the drug delivery device, each of theoptical sensors being arranged to detect the emitted light reflectedfrom the externally visible path.

Each of the optical sensors may be a PIN diode, for instance.

The array of optical sensors may be arranged within the sensor devicesuch that, when the sensor device is attached to the drug deliverydevice, the optical sensors of the array are generally equidistantlyspaced from one another along a length corresponding to the length ofthe visible path.

The array of optical sensors may extend generally along an axis.

When the sensor device is attached to the drug delivery device, the axisalong which the array of optical sensors may extend may be generallyparallel to a longitudinal axis of the drug delivery device.

The sensor device may comprise:

a sensing arrangement arranged within the sensor device such that, whenthe sensor device is attached to the drug delivery device, the sensingarrangement is operable to read encoded information that is externallyvisible on the drug delivery device, wherein the circuitry is configuredto determine, based on the encoded information, information relating tooperation of the drug delivery device.

Here, the circuitry may be configured to determine based on the encodedinformation and the location along the path of the first movableelement, information relating to a drug dose to which the drug deliverydevice is currently dialed.

Optionally, at least part of the encoded information is provided on atleast a second movable element of the drug delivery device, the secondmovable element being rotatable within the drug delivery device andwherein the circuitry is configured to determine based on the encodedinformation a degree of rotation of the second movable element withinthe drug delivery device. The circuitry may be configured to determinethe information relating to currently-dialed drug dose based on thelocation along the visible path of the first movable element and thedegree of rotation of the second movable element.

The movement of the first and second movable elements may beinterdependent.

The circuitry may be configured to determine based on the encodedinformation an operational mode of the drug delivery device.

The encoded information may be dependent on a position of a furthermovable element within the drug delivery device, the position of whichmay be dependent on whether the drug delivery device is in dialing modeor dispensing mode.

The circuitry may be configured to determine based on the encodedinformation a drug for which the drug delivery device is being used todispense.

At least part of the encoded information may be externally visiblethrough an aperture or window formed in the delivery device, wherein thesensing arrangement is arranged within the sensor device such that, whenthe sensor device is attached to the drug delivery device, the sensingarrangement is operable to detect light received from the aperture orwindow. Here, the sensing arrangement may comprise:

a light source arrangement configured to project light towards theaperture or window in the drug delivery device when the sensor device isattached to the drug delivery device; and a photosensor arrangementconfigured to receive light reflected from the aperture or window.

The light source arrangement may comprise a light source and a lightguide arranged together to project light towards the aperture or windowin the drug delivery device.

The photosensor arrangement may comprise a photo-sensor configured toreceive light the aperture or window and one or more lenses configuredto focus an image of the aperture or window towards the photo-sensor.

Another aspect of the invention provides a drug delivery systemcomprising:

the sensor device above; and

the drug delivery device having the first movable element which isconfigured to move along the externally visible path.

The first movable element may be moveable along an underlying elementand is configured such that movement of the first movable element in aparticular direction causes the underlying element to become visible atsuccessive locations along the externally visible path, wherein at leastpart of the first movable element has a first reflectance and theunderlying element has a second, different reflectance.

The first moveable element may be movable relative to the underlyingelement such that movement in a first direction along the externallyvisible path causes an increasing length of the underlying element tobecome visible in the externally visible path.

Alternatively, the first moveable element may comprise a first regionhaving the first reflectance and a window or aperture provided in thefirst region through which the underlying element is externally visible.

The drug delivery device may comprise:

a drug dispensing mechanism, actuation of which causes the drug to bedispensed to the user; and

a further movable element configured to be movable from a first positionto a second position in response to actuation of the drug dispensingmechanism, a first part of the further movable element being externallyvisible through a window or aperture of the drug delivery device whenthe further movable element is in one of the first and second positions,

wherein the sensor device comprises a sensing arrangement overlying thewindow or aperture and configured to output signals to the circuitrybased on which the circuitry is operable to determine whether or not thefirst part of the further movable element is externally visible throughthe aperture or window and thereby to determine when the drug dispensingmechanism has been actuated.

The drug delivery device may comprise a second movable element which isrotatable within the device, wherein rotation of the second movableelement and movement of the first movable element are interdependent,the second movable element comprising a code provided around a portionof its exterior, a part of the code being externally visible through awindow or aperture formed in the drug delivery device and wherein thesensor device comprises a sensing arrangement overlying the window oraperture and configured to read the portion of the code that isexternally visible through the window or aperture, the circuitry beingconfigured to determine, based on the externally visible portion of thecode and the position along the path of the first movable element,information relating to drug dose to which the drug delivery device iscurrently dialed.

BRIEF DESCRIPTION OF THE FIGURES

For a more complete understanding of example embodiments of the presentinvention, reference is now made to the following description taken inconnection with the following Figures, in which:

FIG. 1 shows two views of a drug delivery device 1 with which a sensordevice according to various embodiments of the invention may be used;

FIGS. 2A to 2E are illustrative simplified views of various components,and combinations of components, of a drug delivery device such as thatof FIG. 1 with which a sensor device according to various embodimentsmay be used;

FIG. 3 shows is a simplified cut-away view of the drug delivery devicecomponents depicted in FIG. 2D in combination with part of a sensordevice according to various embodiments of the invention;

FIGS. 4A to 4D show various views of the drug delivery device and thesensor array of the sensor device of FIG. 3 for the purpose ofillustrating the operation of the sensor device;

FIG. 5 shows a different arrangement of the sensor array relative to thedrug delivery device to that shown in FIGS. 3 and 4A to 4D;

FIGS. 6A to 6C are illustrative simplified views of various componentsof an alternative drug delivery device with which sensor devicesaccording to various embodiments of the invention may be used;

FIG. 6D is a simplified view of a sensor device according to embodimentsof the invention in combination with the drug delivery device of FIGS.6A to 6C;

FIG. 7 is simplified block diagram of a sensor device according toembodiments of the invention;

FIG. 8 shows an example of a physical arrangement of the components ofthe sensor device depicted in FIG. 7;

FIG. 9 shows the sensor device as depicted in FIG. 8 in situ on a drugdelivery device;

FIGS. 10A and 10B show examples of encoded information which may be readby the sensor device according to various embodiments of the invention;and

FIG. 11 shows a component of a drug delivery device for use with thesensor device according to various embodiments of the invention.

DETAILED DESCRIPTION

In the description and drawings, like reference numerals refer to likeelements throughout.

FIG. 1 shows two views of a drug delivery device 1, in this example aninjection device, with which a sensor device (also referred to as asupplementary device—not shown) according to various embodiments of theinvention may be used.

The drug delivery device 1 of FIG. 1 is configured such that a user isable to adjust the drug dosage (or number of drug doses) that is to bedelivered (or dispensed) using the device 1. In the example of FIG. 1,this is achieved by rotating (or dialing) a dose selector 10 whichcauses an internal dialing mechanism (not shown) to adjust an amount ofthe drug that is to be dispensed once a drug delivery mechanism (notshown) is actuated. In this example, the drug delivery mechanism isactuated by pressing a button 11 on the device.

The drug delivery device 1 comprises an external housing 12 in which isformed at least one aperture or window 13A, 13B. As will be appreciated,an aperture may simply be a cut-away area of the external housing 12,whereas a window may be a transparent portion of the housing throughwhich components of the device may be seen. For convenience, the atleast one aperture or window 13A, 13B, will hereafter simply be referredto as the at least one window.

The at least one window 13A, 13B allows a movable gauge element 14 to bevisible from the exterior of the housing 12. The drug delivery device isconfigured such that as the dose selector 10 is dialed, the movablegauge element 14 is caused to be moved thereby to indicate a selecteddose to the user. More specifically, as the dose selector 10 is dialed,the gauge element 14 moves axially along an underlying surface 15A, 15Bthereby to indicate the selected dose. In the example of FIG. 1, asurface 15A underlying at least part of the gauge element 14 comprises anumber sleeve 15A. The number sleeve 15A has numbers indicative of drugdoses provided on its outer surface, with the number indicating thecurrently selected dose being visible through the at least one window13A, 13B. In this example, the number sleeve 15A is visible through agauge window (or aperture) 14-1 formed in the movable gauge element.Other parts of the movable gauge element 14 are discussed below.

The uppermost view of the drug delivery device 1 shown in FIG. 1illustrates the situation before any dialing has been performed.Consequently, the movable gauge element 14 is at its first (or initial)position at a first end of the path along which it is able to move. Inthis example, when the movable gauge element 14 is at the first end ofits path, the portion of the number sleeve 15A that is visible throughthe gauge window 14-1 shows the number zero (i.e. a zero dose).

The bottommost view of the drug delivery device 1 shown in FIG. 1illustrates the situation after dialing has been performed.Consequently, the movable gauge element 14 has moved axially along thepath that is visible through the first window 13A away from its firstposition. In this example, the device 1 has been dialed to its maximumdose and as such, the movable gauge element 14 has moved to the secondend of its path. The maximum dose in this example is “100” and so theportion of the number sleeve 15A that is visible through the gaugewindow 14-1 shows the number “100”.

In this example, the device 1 comprises first and second windows 13A,13B. The number sleeve 15A underlies and is visible through the firstwindow 13A, whereas a further underlying element 15B underlies and issometimes visible through the second window 13B. The further underlyingelement 15B may or may not include any numbers. The further underlyingsurface 15B is visually distinguishable from a second part 14-2 of themovable gauge element 14 which overlies it and which is configured tomove axially along it. For instance, the second part 14-2 of the movablegauge element 14 may be of a different reflectance to the furtherunderlying surface 15B. For example, one of the gauge element 14 and theunderlying surface 15B may be of a light colour (e.g. may be made of alight coloured polymer) and the other may be of dark colour (e.g. may bemade of a dark coloured polymer). The user may, therefore, be able todetermine the selected dose by determining the proportion of the secondwindow 13A in which the gauge element 14 (specifically, the second part14-2) is visible compared to the proportion in which the furtherunderlying surface 15B is visible. This can be seen from FIG. 1, inwhich, when the device 1 is dialed to its zero dose, the gauge element14 covers the entire length of the path that is visible through thesecond window 13B. In contrast, when the device 1 is dialed to itsmaximum dose, none of the gauge element 14 is visible through the secondwindow. Instead, the further underlying surface 15B is visible along theentire length of the path defined by the second window 13B.

The number sleeve 15A (which is also surface underlying the gaugeelement 14) is also visually distinguishable from the movable gaugeelement 14 which overlies it and which is configured to move axiallyalong it. For instance, gauge element 14 may be of a differentreflectance to the number sleeve 15A. For example, one of the gaugeelement 14 and the underlying surface 15A may be of a light colour (e.g.may be made of a light coloured polymer) and the other may be of darkcolour (e.g. may be made of a dark coloured polymer). In the examplesshown in the Figures, the number sleeve 15A and underlying surface 15Bare of a higher reflectance than the movable gauge element 14.

FIGS. 2A to 2E are simplified schematics of components of a drugdelivery device such as that of FIG. 1. The purpose of FIGS. 2A to 2E isto illustrate the operation of a drug delivery device 1 such as that ofFIG. 1; they are not intended to be accurate representations of theexact design of the components.

FIG. 2A is a simplified schematic of the number sleeve 15A. The sleeve15A has numbers provided on its surface. In some examples, the numbers,ranging from the minimum dose to the maximum dose, may be providedhelically around the surface of the number sleeve.

FIG. 2B is a simplified schematic of a movable gauge element 14. Thegauge element 14 comprises a first section 14-4 in which the gaugewindow 14-1 is provided. In this example, the first section is 14-1 acollar which is configured to encircle the number sleeve 15A (as can beseen in FIGS. 2C and 2D). Extending in opposite directions from thefirst section 14-4 are the second part 14-2 and a third part 14-2. Thesecond and third parts 14-2, 14-3 extend generally parallel to thelongitudinal axis of the number sleeve.

The second part 14-2 of the movable gauge element is configured toextend from the first part 14-2 by a length sufficient to fill theentire second window 13B when the movable gauge is in its firstposition. The second part 14-2 may also serve to obscure a portion ofthe exterior surface of the number sleeve 15A, when the gauge elementmoves away from its first position. The third part of the movable gaugeelement 15-3 is configured to obscure a portion of the exterior surfaceof the number sleeve 15A, when the gauge elements moves between itsfirst and second positions. In this way, only the portion of the numbersleeve that underlies the gauge window 14-1 is visible through the firstwindow 13A of the device housing 12.

The number sleeve 15A is rotatable about its longitudinal axis withinthe device housing 12. As such, the number sleeve 15A may be referred toas a movable (or rotatable) element. Rotation of the number sleeve 15Ais in some embodiments caused by rotation of the dose selector 10.

The rotational movement NS_(R) of the number sleeve 15A and axialmovement G_(E) of the gauge element 14 are interdependent. Put anotherway, the dialing mechanism of the device 1 is configured such that whennumber sleeve 15A is caused to rotate, the gauge element 14 is caused tomove or translate axially along its path. Moreover, the degree ofrotation of the number sleeve 15A corresponds proportionally to theextent of axial movement of the gauge element 14.

FIG. 2C shows the gauge element 14 in its initial position in which, inthis example, it indicates a zero dose. FIG. 2D shows the number sleeve15A and gauge element 14 following rotation of the number sleeve 15A andtranslation of the gauge element 14 from its first position. FIG. 2Eshows this arrangement of FIG. 2D within a simplified version of thedevice housing 12.

Various dialing mechanisms for adjusting a dose to be delivered to auser which transform rotation of a dose selector 10 into rotationalmovement of a number sleeve 15 A and axial movement of a gauge element14 (as described above) are known in the art. Two such mechanisms aredescribed in WO2013/110538A1 and WO2008/145171A1. As such mechanisms(and also drug delivery mechanisms which cause delivery of the drug oncethe dose has been dialed) are known in the art, they will not bedescribed herein in any detail.

FIG. 3 shows an extremely simplified cut-away view of the components ofthe delivery device 1 as depicted in FIG. 2D and a simplified schematicillustration of a sensor device 2 for use with a delivery device 1 suchas that described with reference to FIGS. 1 to 2D.

The sensor device 2 comprises an array 20 of optical sensors 20-1 to20-5 arranged such that, when the sensor device 2 is in place on thedrug delivery device 1, each optical sensor 20-1 to 20-5 in the array 20is operable to detect light received from a different location along anexternally visible path defined by one of the at least one window 13A,13B. Each optical sensor 20-1 to 20-5 then outputs a signal indicativeof an amount of detected light. The sensor device 2 further comprisescircuitry 21 configured to receive the signals output from the opticalsensors 20-1 to 20-5 of the array 20 and, based on the received signals,to determine information associated with a location along the pathdefined by the window 13A, 13B of the movable gauge element 14. Thecircuitry 21 may be further configured to control operation of the array20.

When the sensor device 2 is in place adjacent an externally visible pathof the drug delivery device 1, the optical sensors 20-1 to 20-5 of thearray 20 are spaced along the path. The optical sensors 20-1 to 20-5 maybe substantially equidistantly spaced from one another along a lengthgenerally corresponding to the length of the visible path. The lengthover which the optical sensors 20-1 to 20-5 are spaced may not beexactly the same as the length of the visible path along which the gaugeelement 14 moves but may be dependent on the length of the visible pathwith which the sensor device 2 is designed to be used.

In some embodiments, the array 20 of optical sensors 20-1 to 20-5extends generally along an axis which, when the sensor device 2 iscoupled to the delivery device 2, is generally parallel with the axisalong which the moveable gauge element 14 is configured to move. Theaxis along which the array 20 of optical sensors extends is thereforealso generally parallel with the longitudinal axis of the window 13A,13B that it overlies. The axis along which the array 20 extends is alsogenerally parallel to the longitudinal axis of the drug delivery device1. The optical sensors 20-1 to 20-5 may be equidistantly spaced from oneanother along the axis.

Each of the optical sensors 20-1 to 20-5 has a corresponding lightsource (not shown) arranged to emit light towards the externally visiblepath (defined by the window 13A, 13B) when the sensor device 2 isattached to the drug delivery device 1. The light emitted by each lightsource is then reflected off the visible path back to the correspondingoptical sensor 20-1 to 20-5. Each optical sensor 20-1 to 20-5 may beprovided in a single package with its corresponding light source. Eachof the optical sensors 20-1 to 20-5 may comprise a PIN photodiode, forexample. Each of the light sources may, for instance, comprise an LED.

Because the visible path towards which the array 20 is oriented isformed by the gauge element 14 and/or the underlying element 15A, 15B,which are visually distinguishable from one another (e.g. because theyare different colours), the amount of light reflected back to each ofthe optical sensors 20-1 to 20-5 will vary in dependence on the positionof the movable gauge element 14 along its path.

The optical sensors of the array 20 may be configured such that, whenthe amount of detected light is one-side of a threshold, an outputsignal having a first value is provided to the circuitry 21 and, whenthe amount of detected light is on the other side of the threshold, anoutput signal having a second value is provided to the circuitry. Inexamples in which the optical sensors 20 are PIN photodiodes, when theamount of detected light is below a threshold, the output signal is LOWand when the detected light is above the threshold, the output is HIGH.As will be appreciated the exact threshold of the optical sensors andthe values of the signals output by the sensors may be dependent on anumber of factors including, for example, the bias applied to thesensors.

The drug delivery device 1 may be configured such that either one of theunderlying surface 15A, 15B and the movable gauge element 14 has areflectance which is sufficiently low such that the light reflectedtherefrom falls on one side of the sensor threshold. The other one ofthe underlying surface 15A, 15B and the movable gauge element 14 has areflectance which is sufficiently high such that the light reflectedtherefrom falls on the other side of the threshold. In the examplesdescribed herein, the underlying surface 15A, 15B has a sufficientlyhigh reflectance to overcome the sensor threshold, whereas the movablegauge element 14 has a sufficiently low reflectance so as not to surpassthe sensor threshold. Consequently, in examples in which the sensors20-1 to 20-5 are PIN photodiodes, sensors located above a section ofpath at which the gauge element 14 is externally visible output a LOWsignal, whereas sensors located above a section of path at which theunderlying element 15A, 15B is visible output a HIGH signal.

FIGS. 4A and 4D illustrate the operation of the sensor device 2 when themovable element is at different positions along its path. In thisexample, the array 20 comprises first to fifth optical sensors 20-1 to20-5, with the first sensor 20-1 being located above a first end of thewindow 13B at which the movable gauge element 14 is present only whenthe minimum dose is dialed. The fifth sensor 20-5 is located above asecond end of the window 13B at which the gauge element 14 isvisible/present unless the maximum dose is dialed.

In FIG. 4A, the movable gauge element 14 is at its initial position(e.g. when the dose is at its minimum). Consequently, the dark coloured(and low reflectance) gauge element 14 covers the entire path underlyingthe array 20. As such, a sufficient quantity of light to surpass thethreshold is not detected by any of the sensors 20-1 to 20-5. As such,all five sensors 20-1 to 20-5 output a LOW signal.

In FIG. 4B, the gauge element 14 has moved to approximately the 20% doseposition. In this situation, the light coloured (and high reflectance)underlying surface 15B is visible to the first sensor 20-1.Consequently, sufficient light to surpass the threshold is reflectedback from the underlying surface 15B to the first sensor 20-1 and so thefirst sensor outputs a HIGH signal.

As the gauge element 14, is below each of the other sensors 20-2 to20-5, these output a LOW signal.

In FIG. 4C, the gauge element 14 has moved to approximately the 40% doseposition and so the light coloured (and high reflectance) underlyingsurface 15B is visible to the first and second sensors 20-1, 20-2, whichtherefore output a HIGH signal. The third to fifth sensors 20-3 to 20-5output a LOW signal.

Finally, in FIG. 4D, the gauge element 14 has moved to approximately the80% dose position and so the light coloured (and high reflectance)underlying surface 15B is visible to the first to fourth sensors 20-1 to20-4, which output a HIGH signal. The fifth sensor element outputs a LOWsignal.

From the above, it is clear how the signals output from the opticalsensors 20-1 to 20-1 can be used by the circuitry 21 to determine thedialed dose. This is illustrated in Table 1 below:

TABLE 1 1^(st) 2^(nd) 3^(rd) 4^(th) 5^(th) Determined sensor sensorsensor sensor sensor Dose output output output output output  0% LOW LOWLOW LOW LOW 20% approx. HIGH LOW LOW LOW LOW 40% approx. HIGH HIGH LOWLOW LOW 60% approx. HIGH HIGH HIGH LOW LOW 80% approx. HIGH HIGH HIGHHIGH LOW 100% HIGH HIGH HIGH HIGH HIGH

FIG. 5 shows an alternative position of the array of optical sensors 20with respect to the delivery device 1 to that shown in FIGS. 3 and 4A to4D. More specifically, in FIG. 5, the sensor array 20 is positioned tooverlie the first window 13A, through which the number sleeve 15 isvisible via the gauge window 14-1. When used in this configuration, allof the optical sensors 20-1 to 20-5 will provide the same output exceptthat overlying the current location of the gauge window 14-1. This isbecause, in the first window, the gauge element 14 fills the entirewindow except for the part at which the gauge window 14-1 is positioned.As such, where the gauge element 14 is of low reflectance compared tothe number sleeve 15B, only the sensor element located above the gaugewindow 14-1 will detect sufficient light to surpass its threshold. Inthe example of FIG. 5, the circuitry 21 may be configured to determinethe location of the movable element 14 within the first window 13A basedon the signals output by the sensors in the array, as shown in Table 2:

TABLE 2 1^(st) 2^(nd) 3^(rd) 4^(th) 5^(th) Determined sensor sensorsensor sensor sensor Dose output output output output output  0% approxLOW LOW LOW LOW LOW 20% approx. HIGH LOW LOW LOW LOW 40% approx. LOWHIGH LOW LOW LOW 60% approx. LOW LOW HIGH LOW LOW 80% approx. LOW LOWLOW HIGH LOW 100% approx.  LOW LOW LOW LOW HIGH

Although the above examples describe optical sensors having a thresholdand two distinct outputs (HIGH and LOW), it will be appreciated thatsensors which do not have such a threshold and which instead output asignal from which the amount of detected light is derivable (e.g.because the output signal is proportional to the amount of lightdetected) may instead be used. In such examples, the circuitry 21 isstill configured to determine, based on the received signals, whetherthe movable gauge element 14 or the underlying surface 15A, 15B isvisible to a particular optical sensor.

As will be appreciated, the accuracy with which the dose can bedetermined using the array 20 of optical sensors 20-1 to 20-5 is limitedby the number of sensors in the array, with a higher number of sensorsproviding a higher accuracy. An alternative mechanism for improving theaccuracy of the sensor device 2 (instead of simply increasing the numberof sensors in the array 20) is discussed with reference to FIGS. 6A to6D.

FIG. 6A shows an example of a rotatable element 65A, in this instance anumber sleeve 65A, which may form part of a drug delivery device 6 foruse with sensor devices 1 according to embodiments of the invention.FIGS. 6B and 6C show two different simplified views of a delivery device6 including the rotatable element 65A of FIG. 6A. The delivery device ofFIGS. 6 and 6A may be generally the same as that described withreference to the previous figures except for the differences describedbelow.

As with the previously described delivery device 1, the rotation of therotatable element 65A is interdependent with the axial movement of themovable gauge element 14. The degree of rotation may be proportional tothe axial movement of the movable gauge element 14. In the examples ofFIG. 6A, the rotatable element 65A has, provided around its exteriorsurface, a visually-distinguishable code 66 for allowing its rotationalorientation to be determined. For instance, the code may enabledetermination by the sensor device 2 as to whether the rotationalorientation is zero degrees, 90 degrees, 180 degrees, 270 degrees. Arotation of zero degrees corresponds to the initial orientation of therotatable element 65A when the dose of the delivery device 6 is dialedto its minimum. It also corresponds to the orientation after everycomplete rotation of the rotatable element 65A. In other examples, thecode 66 may allow a higher or lower accuracy with regards the rotationalorientation of the rotatable element 65A. For instance, the code 66 mayallow an accuracy of the 30 or 45 degrees or may allow an accuracy ofonly 180 degrees. The code 66 may take any suitable form so long as itallows the rotational orientation of rotatable element to be determinedby the sensor device 2. In this example, the code 66 is provided at anend of the number sleeve 65A.

The housing 12 of the drug delivery device 6 includes a further apertureor window 63 through which a portion of the rotatable element 65A, onwhich part of the code 66 is provided, is visible. The further window 63is positioned and oriented relative to the rotatable element 65A suchthat a portion of the code is externally visible through the furtherwindow 63 regardless of the rotational orientation of the rotatableelement 65A. The further window 63 is positioned and oriented relativeto the rotatable element 65A such that, as the rotatable element rotatesthrough a single complete rotation, a different section of the code 66is visible at each rotational orientation. The further aperture is, inthis example, provided on a different side of the device housing 12 (or,if the housing is cylindrical or otherwise rounded, around the exteriorsurface of the device housing 12) from the at least one window 13A, 13Bthrough which the movable gauge element 14 is visible. In this way, themovable gauge element 14 does not obstruct the code from view.

As shown schematically in FIG. 6D, the sensor device 2 may, in additionto the array 20 of optical sensors 20-1 to 20-5, include a furthersensing arrangement 23. The sensing arrangement 23 is arranged withinthe sensor device 2 such that, when the sensor device 2 is attached tothe drug delivery device 6, the sensing arrangement 23 is operable toread encoded information 660 (which may include the code 66) that isexternally visible on the drug delivery device 6. In this example, atleast part of the encoded information 660 is visible through the furtherwindow 63. In some other examples, such as are discussed below, at leastpart of the encoded information may be provided on a portion of theexterior of the housing 12 which underlies the sensing arrangement 23.

The sensing arrangement 23 may be of any suitable type as long as itenables the encoded information 660 to be read. For instance, thesensing arrangement may be an optical sensing arrangement comprising acamera or a small array of sensing elements, a magnetic or inductivesensing arrangement or a conductance/resistance sensing arrangement.

The circuitry 21 of the sensor device 2 of FIG. 6D is configured todetermine, based on the encoded information 660, information relating tooperation of the drug delivery device 6. In some specific examples, thecircuitry 21 is configured to determine a current dose to which thedevice 6 is dialed, based on the encoded information 660 and the signalsoutput from the optical sensors of the array 20. For instance, thesignals output from the array 20 may be utilised by the circuitry 21 todetermine the number of complete rotations of the rotatable element 65Athat have occurred and the encoded information 660 read by the sensingarrangement 23 may be utilised to determine the rotational orientationof the rotatable element 65A. Put another way, the signals output fromthe array 20 may be used to determine roughly the extent of axialtranslation of the moveable gauge element, with the encoded information660 read by the sensing arrangement being used with the roughdetermination to more precisely determine the extent of translation ofthe movable gauge element 14 (thereby to determine the currently dialeddose).

The array 20 may comprise the same number of optical sensors 20-1 to20-5 as the number of complete rotations of the rotatable element 65Athat are required to move the movable gauge element 14 from its initialto final position. The sensors 20-1 to 20-5 may be distributed adjacentthe visible path of the movable gauge element such that after everycomplete rotation of the rotatable element 65A, the output of asuccessive optical sensor in the array 20 changes. For instance, usingthe example described with reference to FIGS. 4A to 4D and Table 1,after the first complete rotation of the rotatable element 65A, theoutput of the first sensor 20-1 in the array 20 changes from LOW toHIGH. After the second rotation, the output of the second sensor 20-2changes from LOW to HIGH. After the third complete rotation, the outputof the third sensor 20-2 changes from LOW to HIGH and so on until thefifth complete rotation at which point the output of the fifth sensor20-5 changes from LOW to HIGH. It will thus be appreciated that thesignals output by the sensors of the array 20 can be used to determinethe number of complete rotations.

The encoded information 660 (specifically, code 66) read by the sensingarrangement 23 is then used by the circuitry 21 to determine the extentof any partial rotations of the rotatable element 65A. The determinedextent of partial rotation of the rotatable element 65A is then combinedwith the determined number of complete rotations to determine thecurrently dialed dose of the drug delivery device 6. This determinationis illustrated in Table 3 below:

TABLE 3 1^(st) 2^(nd) 5^(th) Partial sensor sensor 3^(rd) sensor 4^(th)sensor sensor Rotation Dose output output output output output (degrees)0% LOW LOW LOW LOW LOW 0 10% LOW LOW LOW LOW LOW 180 20% HIGH LOW LOWLOW LOW 0 30% HIGH LOW LOW LOW LOW 180 40% HIGH HIGH LOW LOW LOW 0 50%HIGH HIGH LOW LOW LOW 180 60% HIGH HIGH HIGH LOW LOW 0 70% HIGH HIGHHIGH LOW LOW 180 80% HIGH HIGH HIGH HIGH LOW 0 90% HIGH HIGH HIGH HIGHLOW 180 100% HIGH HIGH HIGH HIGH HIGH 0

It will be understood that the accuracy of the sensor device 2 can beimproved by increasing the accuracy with which partial rotations can bedetermined. For instance, in the above example, if quarter rotations(i.e. every 90 degrees) were instead identifiable, the circuitry 21would be able to determine the dialed dose to an accuracy of 5%.

Up until now, the composition of the electronic device 2 has beendescribed at a very high level. FIGS. 7, 8 and 9 depict the sensordevice 2 in more detail.

FIG. 7 is a simplified schematic block diagram of a sensor device 2according to various embodiments. As described above, the sensor device2 comprises the array 20 of optical sensors 20-1 to 20-5 which areconfigured to output signals to the circuitry 21. In some embodiments,the device 2 comprises the further sensing arrangement 23 which isconfigured to output signals indicative of the encoded information tothe circuitry 21.

The circuitry 21 may be of any suitable composition and may comprise anycombination of one or more processors and/or microprocessors 210 (forsimplicity, hereafter referred to as “the at least one processor”)suitable for causing the functionality described herein to be performed.

The circuitry 21 may additionally or alternatively comprise anycombination of one or more hardware-only components such as ASICs, FPGAsetc. (which are not shown in FIG. 7).

The circuitry 21 may further comprise any combination of one or morenon-transitory computer readable memory media 211, such as one or bothof ROM and RAM, which is coupled to the at least one processor 210. Thememory 211 may have computer-readable instructions 211A stored thereon.The computer readable instructions 210, when executed by the at leastone processor 210 may cause the sensor device 2 to perform thefunctionality described in this specification, such as controllingoperation of the array 20 and sensing arrangement 23 and interpretingthe signals received therefrom.

The sensing arrangement 23 comprises at least a light source 23-2 and aphotosensor 23-1. The light source 23-2 is for illuminating the encodedinformation 66 that is visible within the further window 63 formed inthe device housing 62. The photosensor 23-1 is configured read theencoded information by detecting an image (which includes the encodedinformation 660) which is visible to the photosensor (i.e. whichunderlies the photosensor). The image is detected by detecting the lightreflected back from different parts of the surface(s) on which the imageis provided. The encoded information 660 is then passed to the circuitry21. The sensing arrangement 23 may comprise further non-electricalcomponents, which are not shown on FIG. 7. These non-electricalcomponents of the sensing arrangement 23 are described with reference toFIG. 8.

The sensor device 2 may further comprise one or both of a display screen24 (such as an LED or LCD screen) and a data port 25. The display screen24 may be operable under the control of the circuitry 21 to displayinformation regarding operation of the drug delivery device 1 to theuser. For instance, the information determined by the sensor device 2may be displayed to the user. The information determined by the sensordevice 2 may include the dialed dose. Other information which can bedetermined by the sensor device 2 includes the drug being dispensed, themode of the drug delivery device 1, 6, and or a history ofpreviously-dispensed doses. The determination of this “otherinformation” is discussed below with respect to FIGS. 10A, 10B and 11.

The data port 25 may be used to transfer stored information relating tothe operation of the drug delivery device 6 from the memory 211 to aremote device such a PC, tablet computer, or smartphone. Similarly, newsoftware/firmware may be transferred to the sensor device via the dataport 25. The data port 25 may be a physical port such as a USB port ormay be a virtual, or wireless, port such as an IR, WiFi or Bluetoothtransceiver.

The sensor device 2 may further comprise a removable or permanent(preferably rechargeable with e.g. photovoltaic cells) battery 26 forpowering the other components of the device 2. Instead of the battery26, a photovoltaic or capacitor power source may be used. Otherelectrical components which are not shown in FIG. 7, but which maynonetheless be included in the sensor device 2 include a trigger buffer27-1, a regulator 27-2, a voltage suppressor 27-3 and a charger chip27-4, for charging the rechargeable battery if present.

FIG. 8 shows an example of a physical arrangement of the components ofthe sensor device of FIG. 7. The optical sensors 20-1 to 20-5 of thearray 20 are arranged on a first surface of a PCB 28-1 in a way that isdetermined by the shape of the visible path of the movable element 14with which the sensor device 2 is designed to be used. In the examplesdescribed herein, the visible path is linear and, consequently, theoptical sensors 20-1 to 20-5 of the array 20 are linearly arranged onthe PCB 28-1. When the sensor device 2 is attached to the drug deliverydevice 1, 6, the first surface of the PCB 28-1 faces the at least onewindow 13A, 13B of the drug delivery device 1, 6.

One or more of: the light source 23-2 of the sensor arrangement 23, theat least one processor 210, the memory 211, the charger chip 27-4, thevoltage suppressor 27-3, the regulator 27-2 and the trigger buffer 27-1may also be provided on the first surface of the PCB 28-1.

The screen 24 is provided on the opposite side of the PCB to the 28-1 tothe array 20 of optical sensors 20-1 to 20-5, such that it is visible tothe user when the sensor device 2 is attached to the drug deliverydevice 1, 6. The sensor device 2 may be configured so as to extend overthe entire area of the at least one window 13A, 13B such that the atleast one window 13A, 13B is not visible to the user when the sensordevice 2 is attached.

When the drug delivery device 6 includes the further window 63 which islocated on a different side of the device housing 62 to the at least onewindow 13A, 13B in which the movable gauge element 14 is visible, thephotosensor 23-1 of the sensing arrangement 23 may not be provided onthe PCB 28-1. Instead, the photosensor 23-1 may be provided on a supportelement 28-2 which extends from the PCB 28-1. In the example of FIG. 1,the support element 28-2 extends perpendicularly from the PCB, such thatwhen it is attached to the drug delivery device 6, it wraps around aside of the device 6.

As will be appreciated the exact physical arrangement of the componentswithin the sensor device 2 may not be crucial as long as, when thesensor device 2 is attached to the drug delivery device 1, 6, the array20 of optical sensors is aligned with and faces the visible path of themovable element 14. In embodiments including the further sensingarrangement 23, it may also be important that the photosensor 23-1 ofthe sensing arrangement 23 is positioned so as to overlie further window63 formed in the housing 12 of the drug delivery device 6.

The sensing arrangement 23, in this example, further comprises a lightguide 23-3 for guiding the light from the light source 23-2 to thefurther window 63 of the drug delivery device 6. The sensing arrangement23 also comprises a lens array 23-4 for focussing on the photosensor23-1 the light reflected back from the surface(s) underlying thephotosensor 23-1. Put another way, the lens array 23-4 is configured tofocus the image, which is provided on the surface(s) underlying thephotosensor 23-1, on to the photosensor 23-2.

FIG. 9 shows the sensor device 2, without a housing, in position on thedrug delivery device 1, 6. Although not shown, the sensor device 2 maybe configured to be removably attached in position on the drug deliverydevice 1, 6. For instance, the housing (not shown) of the sensor device2 may include a coupling mechanism for securely affixing the sensordevice 2 to the drug delivery device 1, 6. Alternatively, any othermeans for securing the sensor device 2 in position on the drug deliverydevice 1, 6 may be used.

As discussed above, the encoded information 660 that is read by thesensing arrangement 23 may include a portion of a code 66 for enablingthe circuitry to determine the rotational orientation of the rotatableelement 15A, 65A. However, in some embodiments, other operationalinformation may alternatively or additionally be included in the encodedinformation 660 that is read by the sensing arrangement. For instance,the encoded information 660 may include a portion 67 (for instance inthe form of a bar code) for indicating the drug that is being delivered.This can be seen in FIGS. 10A and 10B which show examples of twodifferent views of the encoded information that may be visible to thephotosensor of the sensing arrangement 23. At least part of the encodedinformation 660 (such as the portion of the code 66) may be visiblethrough the further window 63 of the drug delivery device 6. The drugindication code portion 67 may be provided on, for instance, a portionof a drug cartridge that is inserted into the drug delivery device 1, 6and which is visible through the further window 63 and so can be read bythe sensing arrangement 23. Alternatively, it may be provided on aportion of the exterior of the delivery device housing 12 that isadjacent the further window 63 and which is also beneath (and soreadable by) the photosensor 23-1 of the sensing arrangement 23 when thesensor device 2 attached to the drug delivery device 1, 6.

The encoded information 660 may further include a portion 68 forindicating a mode of the drug delivery device 1, 6. This can be seen inFIGS. 10A and 10B which show the encoded information 660 when the device1, 6 is in each of a dialing mode and delivery mode. In this example,when the device is in the dialing mode, the mode indicator 68 is notpart of the encoded information (as shown in FIG. 10B) and when thedevice in the delivery mode, the mode indicator 68 is part of theencoded information 660. Consequently, by determining whether or not themode indicator 68 is present in the encoded information 660, thecircuitry 21 can determine the mode of the device 1, 6.

The mode indictor 68 may be provided on an internal element that iscaused to move in response to actuation of the drug delivery mechanism(for instance by pushing the button 11). The movable internal elementand drug delivery mechanism are together configured such that actuationof the drug delivery mechanism thereby to switch from dialing mode todelivery mode, causes the mode indicator 68 to become visible (or todisappear from) within the further window 63. An example of such aninternal movable element 69 is shown in FIG. 11 and is a “locking arm”.When situated within the drug delivery device 16, the locking arm 69 isconfigured to move from a first position to a second position inresponse to actuation of the drug delivery mechanism. The locking arm 69may be further configured to move from the second position back to thefirst position in response to subsequent actuation of the drug dialingmechanism.

The mode indicator 68 is only visible through the window 63 when thelocking arm 69 is in one of the first and second positions. In this way,the sensor device 2 is able to determine the mode of the drug deliverydevice 6 to which it is attached.

In some embodiments, the sensor device 2 is configured to store ahistory of dispensed drug doses. This may be carried out by storinginformation indicative of the currently dialed dose, when a change fromdialing mode to delivery mode is detected based on the mode indicator68. A timestamp indicative of a time at which the mode change occurredmay also be stored in association with the information indicative of thedose. In addition or alternatively, information indicative of the typeof the dispensed drug, which is determined based on the drug indicationcode portion 67, may be stored in association with the dose information.This may be repeated each time a dose of a drug is dispensed

Although the drug delivery devices described herein include two windows13A, 13B through which the movable gauge element 14 is visible, it willbe appreciated (particularly from the discussions of FIGS. 4A to 4D and5) that sensor devices 2 according to embodiments of the invention maybe used with drug delivery devices 1, 6 which include only one of thesewindows 13A, 13B.

It should be realized that the foregoing embodiments should not beconstrued as limiting. Other variations and modifications will beapparent to persons skilled in the art upon reading the presentapplication. Moreover, the disclosure of the present application shouldbe understood to include any novel features or any novel combination offeatures either explicitly or implicitly disclosed herein or anygeneralization thereof and during the prosecution of the presentapplication or of any application derived therefrom, new claims may beformulated to cover any such features and/or combination of suchfeatures.

1. A sensor device (2) removably attachable to a drug delivery device (12), the sensor device comprising: an array (20) of optical sensors arranged within the sensor device such that, when the sensor device is attached to the drug delivery device, the drug delivery device having a first movable element (14) which is configured to move along a path parallel to the longitudinal axis of the drug delivery device, each optical sensor is operable to detect light received at different locations along the linear path and to output a signal indicative of an amount of detected light; and circuitry (21) configured to receive the signals output from the optical sensors and, based on the received signals, to determine information associated with a location along the path of the first movable element.
 2. The sensor device of claim 1, each of the optical sensors having a corresponding light source (23) arranged to emit light towards the externally visible path when the sensor device is attached to the drug delivery device, each of the optical sensors being arranged to detect the emitted light reflected from the externally visible path.
 3. The sensor device of claim 1 or claim 2, wherein the array of optical sensors is arranged within the sensor device such that, when the sensor device is attached to the drug delivery device, the optical sensors of the array are generally equidistantly spaced from one another along a length corresponding to the length of the visible path.
 4. The sensor device of any of claims 1 to 3, comprising: a sensing arrangement arranged within the sensor device such that, when the sensor device is attached to the drug delivery device, the sensing arrangement is operable to read encoded information that is externally visible on the drug delivery device, wherein the circuitry is configured to determine, based on the encoded information, information relating to operation of the drug delivery device.
 5. The sensor device of claim 4, wherein the circuitry is configured to determine based on the encoded information and the location along the path of the first movable element, information relating to a drug dose to which the drug delivery device is currently dialed.
 6. The sensor device of claim 5, wherein at least part of the encoded information is provided on at least a second movable element of the drug delivery device, the second movable element being rotatable within the drug delivery device and wherein the circuitry is configured to determine based on the encoded information a degree of rotation of the second movable element within the drug delivery device.
 7. The sensor device of claim 6, wherein the circuitry is configured to determine the information relating to currently-dialed drug dose based on the location along the visible path of the first movable element and the degree of rotation of the second movable element.
 8. The sensor device of any of claims 4 to 7 wherein the circuitry is configured to determine based on the encoded information an operational mode of the drug delivery device.
 9. The sensor device of any of claims 4 to 8, wherein the circuitry is configured to determine based on the encoded information a drug for which the drug delivery device is being used to dispense.
 10. The sensor device of any of claims 4 to 9, wherein at least part of the encoded information is externally visible through an aperture or window (13) formed in the delivery device, wherein the sensing arrangement is arranged within the sensor device such that, when the sensor device is attached to the drug delivery device, the sensing arrangement is operable to detect light received from the aperture or window.
 11. The sensor device of claim 10, wherein the sensing arrangement comprises: a light source (23) arrangement configured to project light towards the aperture or window in the drug delivery device when the sensor device is attached to the drug delivery device; and a photosensor arrangement configured to receive light reflected from the aperture or window.
 12. A drug delivery system comprising: the sensor device of any of claims 1 to 11; and the drug delivery device having the first movable element which is configured to move along the externally visible path.
 13. The drug delivery system of claim 12, wherein the first movable element is moveable along an underlying element and is configured such that movement of the first movable element in a particular direction causes the underlying element to become visible at successive locations along the externally visible path, wherein at least part of the first movable element has a first reflectance and the underlying element has a second, different reflectance.
 14. The drug delivery system of claim 13, wherein the first moveable element is movable relative to the underlying element such that movement in a first direction along the externally visible path causes an increasing length of the underlying element to become visible in the externally visible path.
 15. The drug delivery system of any of claims 12 to 14, wherein the drug delivery device comprises a second movable element which is rotatable within the device, wherein rotation of the second movable element and movement of the first movable element are interdependent, the second movable element comprising a code provided around a portion of its exterior, a part of the code being externally visible through a window or aperture formed in the drug delivery device and wherein the sensor device comprises a sensing arrangement overlying the window or aperture and configured to read the portion of the code that is externally visible through the window or aperture, the circuitry being configured to determine, based on the externally visible portion of the code and the position along the path of the first movable element, information relating to drug dose to which the drug delivery device is currently dialed. 